sparse-vectors

Introduction

Sparse vectors are vectors that grow as large as they need to. That is, they can be indexed by arbitrarily large nonnegative integers. The implementation allows for arbitrarily large gaps by arranging the entries in a tree.

Usage

(require-extension sparse-vectors)

If you have the numbers extension installed then this extension will be built with an additional variant that supports bignum indices:

make-sparse-vector, sparse-vector-ref and sparse-vector-set! are analogous to make-vector, vector-ref and vector-set!, except that the indices passed to sparse-vector-ref and sparse-vector-set! can be arbitrarily large.

The optional DEFAULT argument to the make-sparse-vector procedure specifies the default value for indices whose elements have not been set. If the element at index i has not been set, (sparse-vector-ref i) returns DEFAULT or #f, if DEFAULT was not specified when creating the vector.

sparse-vector->list is for debugging: It returns a list of the consecutive elements in a sparse vector from 0 to the highest element that has been set. Note that the list will also include all the #f elements for the unset elements.

(set! (sparse-vector-ref sparse-vector index) value) is supported.

Authors

License

Copyright (c) 1993-2006 Richard Kelsey and Jonathan Rees
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